Captain Sir Tom Moore has tested positive for COVID-19.
He has been admitted to hospital, where he is being treated for pneumonia and has tested positive for the virus.
His daughter Hannah confirmed the news in a statement on Twitter, saying: "He was at home with us until today when he needed additional help with his breathing.
"He is being treated in a ward, although he is not in ICU."
She went on to call the care Captain Sir Tom has received as "remarkable", adding: "We understand that everyone will be wishing him well.
"We are, of course, focusing on my father and will update you when we are able to."